Thermotic insulating material and process for making the same.



purposes and for other frran sraarns PATNT @FTQE.

JUSTIN KAY TOLES, OF SAN FRANCISCO,

CALIFORNIA, ASSIGNOR TO UNION FIBRE COMPANY, OF WINONA, MINNESOTA, A CORPORATION OF MINNESOTA.

THERMOTIC INSULATING MATERIAL AND PROCESS FOR MAKING THE SAME.

No Drawing.

This invention relates to a new and origi-.

nal composition of matter adapted for use as thermotic insulating material and for many other purposes; and further relates to the process for making the same.

The'main object of the invention is to furnish a novel and improved material or felt which is exceptionally well adapted for thermotic insulation and for use in the manufacture of wall boards, fiber board, both hard and soft, and is practical and economical to produce commercially, and whichis lighter, cheaper, stronger, more durable and also more highly efficient than materials heretofore used for. thermotic insulating set forth. I

Other objects and the advantages of the invention will be apparent to those skilled in the art from a careful consideration of the following description of the insulating felt and the process for making the same.

My insulating felt is composed-of a binder and a filler. The binder consists of the fibers ofrice straw, which is produced in large quantities and is cheap, and I use these fibers because they are-peculiarly adapted'by reason of their superior felting qualities to produce a tenacious felt. The filler consists of chopped or ground tule, water grasses, or the straws of previously prepared rye, wheat, barley and the like. The use of tule in the composition is preferable because the tule plant is composed of finely divided and hermetically sealed air. cells, and it makes, when broken up, ground, or pulverized and combined with rice straw fiber or other suitable binding fiber, a highly efiicient insulating material. The tule has no natural binding qualities, and when an adhesive binder of suflicient density to hold it together is used, the insulating efliciency of the tule is nullified because the dense adhesive binder acts as a conductor to transmit thermotic changes therethrough, thus permitting the heat or cold to avoid the path Specification of Letters Patent.

purposes as herein,

Patented Oct. 8, 1918.

v Application filed January 10, 1916. Serial No. 71,382.

through the air cells of the tule and establishing a direct thermodynamic communication fromone side of the material to the other by way of the path furnished by the adhesive binder.

The naturally formed air cells of the tule are not destroyed when the tule is ground or finely divided, and the rice straw fiber is -used only in suificient quantity to afford a hinder or interlocking means to hold the ground tule or other filler products together in a compact form. The material so formed has greater insulating efliciency than the usual commercial insulating material, as has been proved by careful laboratory and engi. neering tests.

The process of making insulating material or felt embodying the present invention, consists in first digesting rice straw, preferably in a nominally weak solution of alkali, until the rice straw is disintegrated to' its fiber constituents (a one per cent. or less alkali solution is' preferred) then washing the same in water to rid it of excess alkali, and then introducing ground or chopped tule in the proportion of from one-third to twothirds of tule, according to the density desired, and thoroughly agitatingithe mass in the wash water, so as to thoroughly mix the two ingredients; then passing the mass through moderate squeeze rollers, or otherwise ridding the mass of water; then placing the mass into a bath of any suitable waterproofing compound (a suitable water-proofing' compound is the subject of a separate United States Patent application filed De- 'cember 20, 1917 and bearing Serial No. 67,741 and for this reasonis not herein disclosed) then thoroughly agitating the mass in the water-proofing bath; then passing the mass through moderate squeeze rollers or other- 7 or otherwise brought together, so intermesh and interlock'a's to produce a strong, resilient, and flexible felt. It is not necessary to employ sizing or other substances to hold the fibers together; and, moreover, said fibers act effectively to bind the ground tule into place, the resultant mass making, when dried, an insulating material especially desirable for refrigerator car floors, cold storage plants, battleships, pipe covers and the like...

As heretofore stated, the material may also be used in the manufacture of house insulating wall boards, fiber board, hard and soft,

and many'other analogous articles.

I claim as new and desire to secure by Letters Patent:

1. An insulating felt, comprising a binder composed 'of fibers derived by cooking rice straw in a. weak alkaline solution, 'anda filler of uncooked vegetable tissues.

2. An insulating felt' composed of the long fibers of rice straw, and a filler of tule tissue.

3. The herein-described process of making insulating felt, which consists in first realkali, then washing the fibers and thor oughly mixing the same with uncooked vegetable tissue by agitating the ingredients in water, and finally drying the felt.

4. The herein-described process of making insulating felt, which consists in first reducing the fibers of rice straw to a partially purified condition in. a weak solution of alkali, then washing the fibers to rid them of excess alkali, then mixing the same with un cooked vegetable tissue by thoroughly agitating the ingredients in water, then floating the material, over a drain screen and forming the same into sheets of predetermined size and thickness, and finally drying the felt.

5. The herein-described process of making insulating felt, which consists in first steeping rice straw in a weak alkaline solution to soften the gums and free the fibers, then washing the fibers and mixing the same with -.maoerated vegetable tissue by agitating the ingredients in water, and finally drying the felt.

JUSTIN KAY TOLES. 

